Projector in illumination optical system including phosphor wheel driver

ABSTRACT

A projector in an illumination optical system includes a laser light source, a synchronization signal processor that converts synchronization signals that are synchronized with video signals input from outside the projector into video signals to be used inside the projector, an LD driver that controls a lighting state of the laser light source according to the synchronization signals output from the synchronization signal processor, an LED (Light Emitting Diode) light source, an LED driver that controls a lighting state of the LED light source according to the synchronization signals output from the synchronization signal processor, a rotational state detector that detects a rotational state of a phosphor wheel, and a phosphor wheel driver that, based on a detected result of the rotational state detector, controls the rotational state of the phosphor wheel.

The present application is a Continuation Application of U.S. patentapplication Ser. No. 12/734,553, filed on May 7, 2010, which is based onInternational Application No. PCT/JP2010/051237, filed on Jan. 29, 2010,the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an illumination optical system thatgenerates illumination lights of a plurality of colors for forming imagelights of a plurality of colors, and a projector that projects the imagelights produced by the illumination optical system.

BACKGROUND ART

Technology that uses an LED (Light Emitting Diode) as a light source ofa projector that projects an image onto a screen such as a liquidcrystal projector or a DMD (Digital Micromirror Device) projector hasbeen receiving attention (see Patent Literature 1).

Because an LED has a long lifetime and offers high reliability,projectors that employ an LED as a light source have the advantages oflong lifetime and high reliability.

However, because the brightness of the light of an LED is low for use asa projector, it is not easy to obtain a projected image that hassufficient brightness with a projector employing an LED as a lightsource. The extent to which a display panel can utilize light from alight source as projection light is limited by the etendue. Morespecifically, unless the value of the product of a light-emission areaof a light source and the angle of radiation is made less than or equalto the value of the product of the area of the plane of incidence of thedisplay panel and the capturing angle that is determined by an f-numberof the illumination optical system, the light from the light source cannot be effectively utilized as projection light.

Although the light quantity of a light source that employs an LED can beincreased by increasing the light-emission area, if the light-emissionarea increases, the etendue of the light source will also increase. As alight source for a projector, it is desirable in terms of the limitationproduced by the etendue to increase the light quantity withoutincreasing the light-emission area. However, it is difficult for a lightsource that employs an LED to increase the light quantity withoutincreasing the light-emission area.

CITATION LIST Patent Literature

Patent Literature 1: JP2003-186110A

SUMMARY OF INVENTION Technical Problem

The etendue of a light source that using only a LED is increases. Thepresent invention realizes an illumination optical system with a smalletendue, a longer lifetime, and a high level of brightness.

Solution to Problem

An illumination optical system of the present invention comprises:

a laser light source that generates an excitation light having a firstwavelength;

a phosphor wheel that includes a blue fluorescent light generationregion that generates fluorescent light having a second wavelength bymeans of the excitation light, and a green fluorescent light generationregion that generates fluorescent light having a third wavelength bymeans of the excitation light;

an LED light source that generates light having a fourth wavelength; and

a dichroic mirror that reflects fluorescent light having the secondwavelength and fluorescent light having the third wavelength, and allowslight having the fourth wavelength to pass therethrough to thereby emiteach of the lights in the same direction.

Further, a projector according to the present invention comprises theabove described illumination optical system.

Advantageous Effects of Invention

According to the present invention, since a laser with a high energydensity converges on a phosphor as excitation light, and sincefluorescent light is emitted from the place at which the laser convergesis used, an illumination optical system can be realized that has a smalletendue, a longer lifetime and a higher level of brightness.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram that illustrates the configuration of anexemplary embodiment of an illumination optical system according to thepresent invention.

FIG. 2 is a plan view of phosphor wheel 105 as viewed from laser lightsource 101 side (from the left side towards the right side in FIG. 1).

FIG. 3 is a sectional view illustrating the structure of blue phosphorregion 105 ₁ in FIG. 2.

FIG. 4 is a sectional view illustrating the structure of green phosphorregions 105 ₂ and 105 ₄ in FIG. 2.

FIG. 5 is a block diagram illustrating the circuit configuration of aprojector that uses an illumination optical system according to thepresent invention.

FIGS. 6(a) to (c) are plan views that illustrate the structure ofprincipal parts of a second exemplary embodiment of the illuminationoptical system according to the present invention, and FIGS. 6(d) to (f)are plan views that illustrate the structure of principal parts of athird exemplary embodiment of the illumination optical system accordingto the present invention.

FIG. 7 is a timing chart that illustrates light emission times of asecond exemplary embodiment.

FIG. 8 is a timing chart that illustrates light emission times of athird exemplary embodiment.

FIG. 9 is a block diagram that illustrates the structure of principalparts of a fourth exemplary embodiment of the illumination opticalsystem according to the present invention.

DESCRIPTION OF EMBODIMENTS

Next, exemplary embodiments are described with reference to thedrawings.

FIG. 1 is a block diagram that illustrates the configuration of oneexemplary embodiment of an illumination optical system according to thepresent invention.

The present exemplary embodiment includes laser light source 101, LEDlight source 102, dichroic mirrors 103 and 104, phosphor wheel 105,light tunnel 106, lens groups 107 to 109, and reflection mirrors 110 ₁and 110 ₂.

FIG. 2 is a plan view of phosphor wheel 105 as viewed from the left sidetowards the right side of FIG. 1.

Laser light source 101 generates an excitation laser light of wavelengthλ1. Phosphor wheel 105 includes blue phosphor region 105 ₁ and greenphosphor regions 105 ₂ and 105 ₄ that generate blue fluorescent lightand green fluorescent light, respectively, of wavelengths λ2 and λ3(λ2<λ3) that are longer than wavelength λ1 when an excitation laserlight is incident thereon. Phosphor wheel 105 also includes transparentregion 105 ₃ that allows light to pass through.

First, the properties of each optical element of the present exemplaryembodiment are described.

LED light source 102 generates red light having wavelength λ4 that islonger than wavelength λ3. Thus, according to the present exemplaryembodiment, lights having four wavelengths, λ1 to λ4, are used, and therelationship between the wavelengths is λ1<λ2<λ3<λ4. The reflectingsurfaces of dichroic mirrors 103 and 104 are parallelly arranged.Dichroic mirror 103 reflects only light of λ3, and allows light of λ1,λ2 and λ4 to pass. Dichroic mirror 104 reflects only light of λ2, andallows light of λ1, λ3 and λ4 to pass. In this connection, dichroicmirror 104 may also be provided so as to reflect light of λ1 and λ2, andto allow light of λ3 and λ4 to pass.

FIG. 3 and FIG. 4 are sectional views that illustrate the structure ofblue phosphor region 105 ₁ and green phosphor regions 105 ₂ and 105 ₄.

As shown in FIG. 3, in blue phosphor region 105 ₁, reflective layer 304and blue phosphor layer 305 are formed on substrate 303 that istransparent with respect to wavelengths λ1 to λ4. When excitation laserlight having wavelength λ1 is incident on blue phosphor layer 305, bluephosphor layer 305 generates blue fluorescent light having wavelengthλ2. Reflective layer 304 allows the excitation laser light havingwavelength λ1 to pass therethrough, and reflects blue fluorescent lighthaving wavelength λ2 generated at blue phosphor layer 305. Therefore, asshown in FIG. 3, when excitation laser light 301 having wavelength λ1 isincident from the side of substrate 303, blue fluorescent light 302having wavelength λ2 is emitted from blue phosphor layer 305 side.

As shown in FIG. 4, in green phosphor regions 105 ₂ and 105 ₄,reflective layer 402 and green phosphor layer 403 are formed onsubstrate 303 that is transparent with respect to wavelengths λ1 to λ4.When excitation laser light 301 having wavelength λ1 is incident ongreen phosphor layer 403, green phosphor layer 403 generates greenfluorescent light having wavelength λ3. Reflective layer 402 reflectsgreen fluorescent light having wavelength λ3 generated at green phosphorlayer 403. Therefore, as shown in FIG. 4, when excitation laser light301 having wavelength λ1 is incident from the side of green phosphorlayer 403, green fluorescent light 403 having wavelength λ3 is generatedat green phosphor layer 305, and the thus generated light is reflectedby reflective layer 402 and emitted from the side of green phosphorlayer 305.

Next, the arrangement of an optical system according to the presentexemplary embodiment is described.

When a case is assumed in which there is no phosphor wheel 105, eachmember is arranged so that outgoing light of laser light source 1 passesthrough dichroic mirror 103 and lens group 109, is returned byreflection mirrors 110 ₁ and 110 ₂, and is incident on dichroic mirror103 through lens group 108. The optical axes of lens group 107 and lensgroup 108 and the rotational axis of phosphor wheel 105 are parallel,and the center of rotation of phosphor wheel 105 is midway between theoptical axes of lens group 107 and lens group 108.

The optical axis of laser light source 101 is perpendicular to theoptical axis of LED light source 102. The outgoing light of laser lightsource 101 is incident on phosphor wheel 105 via dichroic mirror 103 andlens group 109. As described above, phosphor wheel 105 includes threekinds of regions, and the action after light is incident on phosphorwheel 105 differs depending on the region that light is incident on.

As shown in FIG. 2, circular phosphor wheel 105 is divided into fourregions, of which blue phosphor region 105 ₁ and transparent region 105₃, and green phosphor region 105 ₂ and green phosphor region 105 ₄ arearranged so as to be symmetrical about a point.

Outgoing light of laser light source 101 is incident on phosphor wheel105 via dichroic mirror 103 and lens group 107. The point of incidencethereof (hereunder, referred to as “primary focal point”) is in any oneof the above described three kinds of regions. When the primary focalpoint is in transparent region 105 ₃, incident light passes throughtransparent region 105 ₃, is returned by reflection mirrors 110 ₁ and110 ₂, and is incident at a secondary focal point in blue phosphorregion 105 ₁ at a position that is symmetrical about a point withrespect to the primary focal point of phosphor wheel 105.

Hereunder, the action after light is incident is described with respectto cases where the primary focal point is green phosphor region 105 ₂and green phosphor region 105 ₄, transparent region 105 ₃, and bluephosphor region 105 ₁, respectively.

When the primary focal point is in green phosphor region 105 ₂ and greenphosphor region 105 ₄, the configuration is as shown in FIG. 4. Greenfluorescent light having wavelength λ3 that is generated at greenphosphor layer 403 is diffused light, and is collimated by lens group107. Thereafter, the green fluorescent light is reflected towards lighttunnel 106 by dichroic mirror 103. Subsequently, the green fluorescentlight passes through dichroic mirror 104, is condensed by lens group109, and is incident on light tunnel 106.

When the primary focal point is transparent region 105 ₃, outgoing lightof laser light source 101 is incident at the secondary focal point inblue phosphor region 105 ₁ from the rear surface of phosphor wheel 105(from the left side of the figure towards the right side in FIG. 1), anda configuration is entered as shown in FIG. 3. Blue fluorescent lighthaving wavelength λ2 generated at blue phosphor layer 305 is diffusedlight, and is collimated by lens group 108. Thereafter, the bluefluorescent light is reflected towards light tunnel 106 by dichroicmirror 104, is condensed by lens group 109, and is incident on lighttunnel 106.

When the primary focal point is blue phosphor region 105 ₁, bluefluorescent light having wavelength λ2 generated at blue phosphor layer305 is collimated by lens group 107, passes through dichroic mirror 103,and is returned to laser light source 101. Thus, blue fluorescent lightgenerated when the primary focal point is in blue phosphor region 105 ₁is not utilized as illumination light. According to the presentexemplary embodiment, when the primary focal point is in blue phosphorregion 105 ₁, laser light source 101 is extinguished, LED light source102 is lit, and red outgoing light having wavelength λ4 of LED lightsource 102 is incident on light tunnel 106 through dichroic mirrors 103and 104 and lens group 109.

As described above, according to an illumination optical system of thepresent exemplary embodiment, when the primary focal point is in greenphosphor region 105 ₂ and green phosphor region 105 ₄, green fluorescentlight is incident on light tunnel 106. When the primary focal point isin transparent region 105 ₃, blue fluorescent light is incident on lighttunnel 106. When the primary focal point is in blue phosphor region 105₁, red light of LED light source 102 is incident on light tunnel 106.The illumination distribution of each of these incident lights insidelight tunnel 106 is uniformized, so that uniformized red light, greenlight, blue light, and green light appear in that order on the outgoinglight side of light tunnel 106 to be used as illumination light. In thisconnection, yellow or magenta may be used as illumination light by usinga yellow phosphor or a magenta phosphor instead of one of the greenphosphors.

FIG. 5 is a block diagram that illustrates a circuit configuration of aprojector that uses an illumination optical system of the presentexemplary embodiment.

A projector illustrated in FIG. 5 includes user interface 501,controller 502, storage portion 503, video signal processor 504,synchronization signal processor 505, LD driver 506, LED driver 507,phosphor wheel driver 508, display element driver 509, rotational statedetector 510, and display element 511, as well as laser light source101, LED light source 102, and phosphor wheel 105 shown in FIG. 1.

User interface 501 accepts instructions input from a user, and outputsthe instructions to controller 502. User interface 501 also displays thecurrent operating state of the projector on a display apparatus (notshown) such as an indicator or a display panel.

Controller 502 controls each component comprising the projector inaccordance with a program stored in storage portion 503.

Storage portion 503 stores a control program of controller 503, ortemporarily stores video data.

Video signal processor 504 converts a video signal input from outsideinto a video signal to be used inside the projector. Since video signalsof the present exemplary embodiment are formed by illumination lights ofrespective colors being output sequentially by an illumination opticalsystem as described above, video signals according to each color aregenerated sequentially.

Synchronization signal processor 505 converts synchronization signalsthat are synchronized with video signals input from outside into videosignals to be used inside the projector. More specifically,synchronization signal processor 505 generates and outputssynchronization signals that show the output timing of video signals ofeach color.

LD driver 506 controls the lighting state of laser light source 101according to synchronization signals output from synchronization signalprocessor 505. LED driver 507 controls the lighting state of LED lightsource 102 according to synchronization signals output fromsynchronization signal processor 505.

Rotational state detector 510 detects the rotational state of phosphorwheel 105, and outputs the detected result to phosphor wheel driver 508.

Phosphor wheel driver 508 controls the rotational state of phosphorwheel 105 so that the color of a video signal indicated by asynchronization signal output by synchronization signal processor 505and a color output by the illumination optical system that indicates therotational state of phosphor wheel 105 detected by rotational statedetector 510 match.

Display element driver 509 drives display element 511 in accordance withvideo signals output by the video signal processor. In this case, areflective image forming element in which a plurality of micromirrorsare arranged in a matrix and which forms an image according to thereflection state of each micromirror, or a transmission-type liquidcrystal display element or reflective liquid crystal display element isused as a display element.

shuusei

According to the projector configured as described above, displayelement 511 that displays images corresponding to each color by means ofillumination light of each color sequentially output from theillumination optical system is illuminated, and reflection images ortransmission images of display element 511 are sequentially projectedthrough a projection optical system (not shown).

Next, another exemplary embodiment is described.

FIGS. 6(a) to (c) are plan views that illustrate the structure ofprincipal parts of a second exemplary embodiment of the illuminationoptical system according to the present invention. FIGS. 6(d) to (f) areplan views that illustrate the structure of principal parts of a thirdexemplary embodiment of the illumination optical system according to thepresent invention.

Phosphor wheel 105 shown in FIG. 2 is equally divided into four regionsin which blue phosphor region 105 ₁ and transparent region 105 ₃, andgreen phosphor region 105 ₂ and green phosphor region 105 ₄ are arrangedso as to be symmetrical about a point. In contrast, in phosphor wheel105′ shown in FIG. 5(a) to (c), the areas of blue phosphor region 105 ₁′and transparent region 105 ₃′ are different from the areas of greenphosphor region 105 ₂′ and green phosphor region 105 ₄′. Since theremaining configuration is the same as in the exemplary embodimentillustrated in FIG. 1, a description thereof is omitted here.

The areas of green phosphor region 105 ₂′ and green phosphor region 105₄′ are made to be twice the areas of blue phosphor region 105 ₁′ andtransparent region 105 ₃′. Since phosphor wheel 105 illustrated in FIG.2 is divided into equal regions, when phosphor wheel 105 is rotatedonce, red light, green light, blue light, and green light appear for thesame period. In contrast, according to the present exemplary embodiment,each time period for which green light appears is twice the time periodfor which red light and blue light appear.

FIG. 7 is a timing chart that shows light emission times of a secondexemplary embodiment.

As shown in FIG. 6(a), when primary focal point 601 is on blue phosphorregion 105 ₁′, laser light source 101 is placed in an extinguishedstate, and LED light source 102 is lit so that red LED light appears(lighting time is taken as period T).

As shown in FIG. 6(b), when primary focal point 601 is on green phosphorregion 105 ₄′, green fluorescent light appears (period 2T).

As shown in FIG. 6(c), when primary focal point 601 is on transparentregion 105 ₃′, blue fluorescent light appears that is generated atsecondary focal point 602 (period T).

Thereafter, when primary focal point 601 is on green phosphor region 105₂′, green fluorescent light appears (period 2T).

Although the generated proportions of each color light, when thephosphor wheel is rotated once, are the same in the exemplary embodimentshown in FIG. 6(d) to (f) as in the exemplary embodiment shown in FIG.6(a) to (c), the phosphor wheel in the exemplary embodiment shown inFIG. 6(d) to (f) is arranged so that green fluorescent light appearsconsecutively.

According to the present exemplary embodiment, the rotational axis ofphosphor wheel 603 is placed in a different position to that of phosphorwheel 105 shown in FIG. 1 and phosphor wheel 105′ shown in FIG. 6(a) to(c), and the size thereof is also changed. Since the remainingconfiguration is the same as in the exemplary embodiment illustrated inFIG. 1, a description thereof is omitted here.

In phosphor wheel 603, blue phosphor region 604 ₁ and transparent region604 ₃ of equal area and green fluorescent light region 604 ₂ of an areafour times the size of the area of blue phosphor region 604 ₁ andtransparent region 604 ₃ are formed in an arc shape. As described above,since the axis of the center of rotation of phosphor wheel 603 is midwaybetween the optical axes of lens group 107 and lens group 108, accordingto the present exemplary embodiment, the relation between primary focalpoint 605 and secondary focal point 606 is not one in which primaryfocal point 605 and secondary focal point 606 are point symmetric withregard to phosphor wheel 603. In the present exemplary embodiment, asshown in FIG. 6(d) to (f), primary focal point 605 and secondary focalpoint 606 have a positional relationship that maintains a predeterminedinterval that matches the interval of blue phosphor region 604 ₁ ortransparent region 604 ₃.

FIG. 8 is a timing chart that shows light emission times of the secondexemplary embodiment.

As shown in FIG. 6(f), when primary focal point 605 is on blue phosphorregion 604 ₁′, laser light source 101 is placed in an extinguished stateand LED light source 102 is lit so that red LED light appears (lightingtime taken as period T).

As shown in FIG. 6(d), when primary focal point 605 is on green phosphorregion 604 ₂′, green fluorescent light appears (period 4T).

As shown in FIG. 6(e), when primary focal point 605 is on transparentregion 105 ₃′, blue fluorescent light appears that is generated atsecondary focal point 606 (period T).

FIG. 9 is a block diagram that illustrates the structure of principalparts of a fourth exemplary embodiment of the illumination opticalsystem according to the present invention.

The present exemplary embodiment includes laser light source 901, LEDlight source 902, dichroic mirror 903, lens groups 904 and 906, andphosphor wheel 905.

Laser light source 901 generates excitation laser light havingwavelength λ1.

LED light source 902 generates red light having wavelength λ4 that islonger than wavelength λ3.

Dichroic mirror 903 allows light having wavelength λ4 to passtherethrough, and reflects light of wavelengths λ1 to λ3.

Similarly to phosphor wheel 105 shown in FIG. 1, phosphor wheel 905includes a blue phosphor region and a green phosphor region thatgenerate blue fluorescent light and green fluorescent light,respectively, having wavelengths λ2 and λ3 (λ2<λ3) that are longer thanwavelength λ1 when an excitation laser light is incident thereon.Phosphor wheel 905 also includes a transparent region.

When laser light from laser light source 901 is emitted towards phosphorwheel 905, blue fluorescent light is generated when the incidenceposition of the laser light is in the blue phosphor region. The bluefluorescent light is collimated by lens group 906, reflected by dichroicmirror 903, and emitted as illumination light through lens group 904.

When the incidence position of the laser light is in a green phosphorregion, green fluorescent light is generated. The green fluorescentlight is collimated by lens group 906, reflected by dichroic mirror 903,and emitted as illumination light through lens group 904.

When the incidence position of laser light is in the transparent region,the laser light passes through phosphor wheel 905 without generatingfluorescent light, and is reflected by dichroic mirror 903 and emitted.Thus, illumination light is not generated when the incidence position oflaser light is in a transparent region. According to the presentexemplary embodiment, when the primary focal point is in the transparentregion, laser light source 901 is extinguished, LED light source 902 islit, and red outgoing light having wavelength λ4 of LED light source 902is emitted as illumination light through dichroic mirror 903 and lensgroup 904.

As described above, in both the second and third exemplary embodiments,red light, green light, blue light, and green light, that are used asillumination light, appear in sequence, and by driving display element511 by means of the arrangement illustrated in FIG. 5, a projector witha high level of brightness and a long lifetime can be realized.

REFERENCE SIGNS LIST

-   101 Laser light source-   102 LED light source-   103, 104 Dichroic mirror-   105 Phosphor wheel-   106 Light tunnel-   107 to 109 Lens group-   110 ₁, 110 ₂ Reflection mirror

The invention claimed is:
 1. A projector in an illumination opticalsystem, the projector comprising: a laser light source; asynchronization signal processor that converts synchronization signalsthat are synchronized with video signals input from outside theprojector into video signals to be used inside the projector; an LDdriver that controls a lighting state of the laser light sourceaccording to the synchronization signals output from the synchronizationsignal processor; an LED (Light Emitting Diode) light source; an LEDdriver that controls a lighting state of the LED light source accordingto the synchronization signals output from the synchronization signalprocessor; a rotational state detector that detects a rotational stateof a phosphor wheel; and a phosphor wheel driver that, based on adetected result of the rotational state detector, controls therotational state of the phosphor wheel such that a color of a videosignal indicated by one of the synchronization signals output by thesynchronization signal processor matches a color output by theillumination optical system that indicates the rotational state of thephosphor wheel detected by the rotational state detector, wherein thephosphor wheel includes a transparent region that allows light of allwavelengths to pass therethrough, and wherein the illumination opticalsystem comprises a recursive mechanism that causes light that has passedthrough the transparent region to be incident on the phosphor wheelagain.
 2. The projector according to claim 1, further comprising: avideo signal processor that converts the video signals input fromoutside the projector into the video signals to be used inside theprojector.
 3. The projector according to claim 2, further comprising: adisplay element driver that drives a display element in accordance withthe converted video signals output by the video signal processor.
 4. Theprojector according to claim 3, wherein the display element includes areflective image forming element in which a plurality of micromirrorsare arranged in a matrix and which forms an image according to areflection state of each of the micromirrors.
 5. The projector accordingto claim 3, wherein the display element includes one of atransmission-type liquid crystal display element and a reflective liquidcrystal display element.
 6. The projector according to claim 1, whereinthe synchronization signal processor outputs the synchronization signalsthat indicate an output timing of video signals of colors.
 7. Theprojector according to claim 1, wherein the laser light source generatesan excitation light having a first wavelength.
 8. The projectoraccording to claim 7, wherein the phosphor wheel comprises a bluefluorescent light generation region that generates fluorescent lighthaving a second wavelength by the excitation light, and a greenfluorescent light generation region that generates fluorescent lighthaving a third wavelength by the excitation light.
 9. The projectoraccording to claim 8, wherein the LED light source generates lighthaving a fourth wavelength.
 10. The projector according to claim 9,further comprising: a dichroic mirror that reflects the fluorescentlight having the second wavelength and the fluorescent light having thethird wavelength, and allows the light having the fourth wavelength topass therethrough to thereby emit each of the lights in a samedirection.
 11. The projector according to claim 10, wherein a reflectivelayer that allows the excitation light to pass therethrough and reflectsthe fluorescent light having the second wavelength and the fluorescentlight having the third wavelength is formed in the phosphor wheel. 12.The projector according to claim 11, wherein, in the blue fluorescentlight generation region, a blue phosphor that generates the fluorescentlight having the second wavelength by the excitation light is formed onthe reflective layer, and wherein, in the green fluorescent lightgeneration region, a green phosphor that generates the fluorescent lighthaving the third wavelength by the excitation light is formed on thereflective layer.
 13. A projector in an illumination optical system, theprojector comprising: a laser light source; a synchronization signalprocessor that converts synchronization signals that are synchronizedwith video signals input from outside the projector into video signalsto be used inside the projector; an LD driver that controls a lightingstate of the laser light source according to the synchronization signalsoutput from the synchronization signal processor; an LED (Light EmittingDiode) light source; an LED driver that controls a lighting state of theLED light source according to the synchronization signals output fromthe synchronization signal processor; a rotational state detector thatdetects a rotational state of a phosphor wheel; a phosphor wheel driverthat, based on a detected result of the rotational state detector,controls the rotational state of the phosphor wheel such that a color ofa video signal indicated by one of the synchronization signals output bythe synchronization signal processor matches a color output by theillumination optical system that indicates the rotational state of thephosphor wheel detected by the rotational state detector, wherein thelaser light source generates an excitation light having a firstwavelength, wherein the phosphor wheel comprises a blue fluorescentlight generation region that generates fluorescent light having a secondwavelength by the excitation light, and a green fluorescent lightgeneration region that generates fluorescent light having a thirdwavelength by the excitation light, and wherein the LED light sourcegenerates light having a fourth wavelength; and a dichroic mirror thatreflects the fluorescent light having the second wavelength and thefluorescent light having the third wavelength, and allows the lighthaving the fourth wavelength to pass therethrough to thereby emit eachof the lights in a same direction, wherein a reflective layer thatallows the excitation light to pass therethrough and reflects thefluorescent light having the second wavelength and the fluorescent lighthaving the third wavelength is formed in the phosphor wheel, wherein, inthe blue fluorescent light generation region, a blue phosphor thatgenerates the fluorescent light having the second wavelength by theexcitation light is formed on the reflective layer, wherein, in thegreen fluorescent light generation region, a green phosphor thatgenerates the fluorescent light having the third wavelength by theexcitation light is formed on the reflective layer, wherein the phosphorwheel includes a transparent region that allows light of all wavelengthsto pass therethrough, and wherein the illumination optical systemcomprises a recursive mechanism that causes light that has passedthrough the transparent region to be incident on the phosphor wheelagain.
 14. The projector according to claim 13, wherein the dichroicmirror comprises: a first dichroic mirror that reflects the fluorescentlight having the third wavelength that is generated when the excitationlight from the green phosphor side is incident on the green fluorescentlight generation region; and a second dichroic mirror that reflects thefluorescent light having the second wavelength that is generated whenthe excitation light that passes through the transparent region isincident from a side of reflective layer on the blue fluorescent lightgeneration region by the recursive mechanism.